During shooting any semi-automatic firearm is subjected to recoil forces.
This phenomenon, a characteristic application of the action-reaction principle, represents the impulse which makes the arm withdraw, due to the impulse the firearm gives to the bullet, firing it.
In the case of long arms, the above-mentioned impulse forces are discharged in the support area of the rifle stock, the shooter's shoulder.
A dynamic analysis of recoils has revealed, for a semi-automatic long arm, the presence of two different acceleration peaks, i.e. two different force impulses.
The first peak, which is larger, is due to the pressure of the cartridge in the barrel during the explosion of the charge, and the first recoil phase is connected to this impulse.
A second peak appears when the mobile masses of the rifle find their run-end, during their withdrawal, producing a second recoil impulse.
Measurements effected during the shooting phase have allowed it to be verified that on the shooter's shoulder, several hundreds of kilograms are discharged, more or less, proportional to the type of cartridge and the weight of the firearm.
It is well-known that the overall energy of the shot which is discharged on the shooter's shoulder can be diluted with time or partially dispersed but never completely eliminated, the dilution with time and dispersion of part of the energy allows the effects on the shooter to be reduced, the firing accuracy to be increased, maintaining the target line for a possible subsequent shoot.
Various devices are known for the damping or reduction of recoil effects, in this field, the Applicant has prepared a recoil damping device described in US patent application 2006/0096148 and a recoil pad in composite material for rifles, object of U.S. Pat. No. 6,594,935.
The devices according to the above two disclosures, have an optimum functioning and provide more than satisfactory damping and adsorbing results. The Applicant, however, by developing the study and testing of recoil damping in firearms, with particular respect to long arms, has surprisingly discovered that it is possible to drastically reduce the recoil effects on the shooter by means of a mechanism suitable for distributing through time, and partially dispersing, the impulsive recoil forces.
According to the known art, the fixing of the stock to the body is effected by means of a centring bolt or screw, suitably threaded at the ends, fixed to the receiver and on which the stock, equipped with a pass-through longitudinal cavity, is engaged.
The stock is then tightened by means of a die to be inserted into the longitudinal cavity, under the recoil pad. The operation is completed by the assembly of the recoil pad. Even if the recoil is reduced, however, the known systems do not eliminate the high stresses inside the firearm, which cause its wear.